Domain Pigeon, the domain finding service that lets you search and browse unclaimed domains, now does the same thing for Twitter usernames. It shows you which names are unclaimed, and puts some of the most recent or popular additions on the front page, where you're able to see which ones other users are clicking on.
As with domain names you can filter down the results to see only names with three or four letters, although to do so you must be a paid, registered user of the site. Those users can also see a larger, and more complete index of names.
Creator Matt Mazur tells me that his service is indexing a few hundred names a day, and that there are "quite a few good ones left." In what feels like an amusing throwback to the days when low-digit ICQ numbers were a hot commodity, Mazur's put a live countdown of how many three-letter usernames are left. As of me writing this there are a little more than 17,800 still available.
Why is this such a big deal? Three is the current minimum Twitter users are able to have. And for a service where the number of followers matters, the smaller your name the more important you may appear to be. More importantly, someone starting a site can check to see if both the domain and Twitter URL are open within the same search.
The one area where this service may become a problem is that could greatly increase the pace in which people are hoarding usernames. This means good business for Domain Pigeon, but a potential surplus of registered--but inactive--users for Twitter.
So do users who snatch these up get to cash out like they can with domain squatting? Potentially. Brands and businesses with trademarks could send Twitter a legal notice to claim what it rightfully theirs (like Marvel did), but for users simply trying to get their first or last name it's turning into a mad, mad rush.